WBBSE Class 9 Life Science Solutions Chapter 1.3D Classification of Kingdom Animalia

Detailed explanations in West Bengal Board Class 9 Life Science Book Solutions Chapter 1.3D Classification of Kingdom Animalia offer valuable context and analysis.

WBBSE Class 9 Science Chapter 1.3D Question Answer – Classification of Kingdom Animalia

Very Short Questions and Answers : (1 mark for each question)

Question 1.
In tripioblastic animals, which germinal layer is present in between ectoderm and endoderm?
Answer:
In triploblastic animals, mesoderm layer is present in between ectoderm and endoderm.

Question 2.
Name a phylum in which mesenchyme is present in between ectoderm and endoderm?
Answer:
In phylum Porifera, mesenchyme is present between ectoderm and endoderm.

Question 3.
Animals of which phylum possess pseudocoelom?
Answer:
Animals of phylum Nematoda possess pseudocoelom.

Question 4.
Members of which phylum use setae or parapodia for locomotion?
Answer:
Animals of phylum Annelida use setae or parapodia for locomotion.

Question 5.
In which group of animals do you find both external and internal segmentation?
Answer:
Animals under phylum Annelida have both external and internal segmentation.

Question 6.
What is paragastric cavity?
Answer:
The cavity, present inside the body of poriferans, is called paragastric cavity.

Question 7.
What is coelenteron?
Answer:
The central tubular gastrovascular body cavity present in Cnidarians is called coelenteron.

Question 8.
What is coelom?
Answer:
Coelom is the fluid-filled cavity inside animal body surrounded by mesodermal lining.

Question 9.
What is haemocoel?
Answer:
Haemocoel is the blood-filled coelomic body cavity, found in arthropods and molluscs.

Question 10.
What is pseudocoeiom?
Answer:
Pseudocoelom is a body cavity, typically seen in nematodes, which is not surrounded by mesodermal lining.

Question 11.
What are setae?
Answer:
Setae are minute bristle-like structures, which earthworms and some other annelids use for locomotion.

Question 12.
What are parapodia?
Answer:
Parapodia are unjointed, lobe-like, paired locomotory organs of annelids, that project laterally from the body segments.

Question 13.
What are comb plates?
Answer:
Comb plates are eight equidistant cilliary plates, present along the meridional line of the body of the members of Ctenophora to help in locomotion.

Question 14.
Members of which phylum is popularly called ‘comb jelly’?
Answer:
Members of phylum Ctenophora are popularly known as ‘comb jelly’.

Question .
Animals under which phylum possess cnidoblast cells?
Answer:
Animals under phylum Cnidaria possess cnidoblast cells.

Question 16.
Members of which phylum have unsegmented body covered with thick cuticle?
Answer:
Members of phylum Nematoda have unsegmented body, covered with thick cuticle.

Question 17.
Members of which phylum have segmented body covered with thick and rigid cuticle?
Answer:
Members of phylum Arthropoda have segmented body, covered with thick and rigid cuticle.

Question 18.
Members of which phylum have metamerically segmented body covered with elastic cuticle?
Answer:
Members of phylum Annelida have metamerically segmented body covered with elastic cuticle.

Question 19.
What is metameric segmentation?
Answer: The repetition of organs and tissues at intervals along the length of the body of an animal, thus dividing the body into a linear series of similar parts or segments, is called metameric segmentation.

Question 20.
Name two phyla whose members show metameric segmentation?
Answer:
Metameric segmentation is seen in the members of Annelida and Arthropoda.

Question 21.
Which group of animals use malpighian tubules for excretion?
Answer:
Members of the class Insecta, under phylum Arthropoda, use malpighian tubules as excretory organs.

Question 22.
Which group of animals use coxal gland for excretion?
Answer:
Scorpions, under class Arachnida of phylum Arthropoda, use coxal gland for excretion.

Question 23.
Which group of animals perform excretion by green gland?
Answer:
Prawns, under class Crustacea of phylum Arthropoda, perform excretion by green gland.

Question 24.
Which group of animals perform respiration by ctenidia?
Answer:
Aquatic snails and mussels, under phylum Mollusca, perform respiration by ctenidia.

Question 25.
Animals under which phylum possess canal system in their body?
Answer:
Animals under phylum Porifera possess canal system in their body.

Question 26.
Animals under which phylum perform locomotion by tube feet?
Answer:
Animals under phylum Echinodermata perform locomotion by tube feet.

Question 27.
Animals under which two classes possess four-chambered heart?
Answer:
Animals under class Aves and Mammalia, possess four-chambered heart.

Question 28.
Which group of vertebrates do not possess teeth?
Answer:
Birds do not possess teeth.

Short Questions and Answers : (2 marks for each question)

Question 1.
What are diploblastic animals?
Answer:
Those animals, whose body consists of two germinal layers, i.e. ectoderm and endoderm, are known as diploblastic animals. Example – Hydra etc.

Question 2.
What are triploblastic animals?
Answer:
Those animals, whose body consists of three germinal layers, i.e. ectoderm, mesoderm and endoderm, are known as triploblastic animals. Example -Tapeworms, earthworms etc.

Question 3.
What is meant by bilaterally symmetrical animals?
Answer:
The animals, which when divided once along the central axis gives two similar halves, are called bilaterally symmetrical animals. Example – Cockroach, human etc

Question 4.
What is meant by radially symmetrical animals?
Answer:
The animals, which when divided in any plane along the central axis gives rise to unlimited number of identical halves, are called radially symmetrical animals. Example – Starfish etc.

Question 5.
What is meant by asymmetrical animals?
Answer:
The animals, which when divided along any plane of the body, does not give rise to equal halves, are called asymmetrical animals. Example-Amoeba, molluscs etc.

Question 6.
What is spongocoel?
Answer:
The single, large central body cavity of the poriferan is called spongocoel. Water enters this cavity through several tiny pores called ostia and exits through a large opening called osculum.

Question 7.
What is meant by canal system?
Answer:
The animals under phylum Porifera have numerous pores all over the body. Through these pores water enters into the body and flows in all direction through a network of fine canals. This is called canal system.

Question 8.
What are ostia and osculum?
Answer:
Ostia: The animals under phylum Porifera possess numerous small pores all over their body which allow water to enter the body. These tiny pores are called ostia.

Osculum: The body cavity of the poriferans opens outside through a narrow circular opening, situated at the free end of their body. This opening is called osculum.

Question 9.
What is mesenchyme?
Answer:
Mesenchyme or mesohyl is a jelly-like layer with a few scattered cells and collagen fibres, present in between the two layers of cells of the body of the members of phylum Porifera and Ctenophora.

Question 10.
What is mesoglea?
Answer:
Mesoglea is a completely non-cellular jellylike layer, typically seen in between ectoderm and endoderm layer of the animals under phylum Cnidaria.

Question 11.
What is cnidoblast cell?
Answer:
Cnidoblast cell is a typical explosive epidermal cell, present in numbers on the tentacles of cnidarians. These cells carry huge secretory organelle, called nematocyst, which injects strong neurotoxin into the body of the preys and attackers.

Question 12.
What is nematocyst?
Answer:
Nematocyst is a typical stinging cell, present in the cnidoblast of cnidarians. This is a vesicle with a hairlike sensory process ejecting, called cnidocil, which discharges strong paralysing material to the preys and attackers.

Question 13.
What is gastrovascular cavity or coelenteron?
Answer:
The central tubular body cavity of cnidarian is called gastro vascular cavity or coelenteron. This cavity functions as both oral cavity as well as digestive cavity. It plays an important role in the digestion process of cnidarians.

Question 14.
What are collobiast cells or lasso cells?
Answer:
Colloblast cells or lasso cells are a kind of adhesive cells, present typically on the tentacles of the members of phylum Ctenophora. These cells are used to capture prey during predation.

Question 15.
What is metamere or somite?
Answer:
The body of annelids are transversely divisible into a series of several similar ring-like segments. These are called somites or metameres.

Question 16.
What is cephalothorax?
Answer:
The body of the members of phylum Arthropoda is segmented into head, thorax and abdomen. But certain crustaceans, such as prawn, crab, lobster etc. have their head fused with thorax. This typical structure is called cephalothorax.

Question 17.
What is mantle?
Answer:
The soft visceral organs of all molluscs remain covered with a typical muscular membrane. This is called mantle. In shelled molluscs, mantle remains just beneath the shell and secrete calcium carbonate and conchiolin, that creates the shell.

Question 18.
What is ambulacrum?
Answer:
Ambulacrum is one of the numerous equidistant radial bands, present medially along the oral side of an arm of echinoderms. It is an elongated area along which numerous tube feet protrude in two rows.

Question 19.
What is water-vascular system?
Answer:
In echinoderms, one ring canal and five sets of radial canals with their branches, connect with numerous tube feet and constitute a well organised vascular system. Through this, water flows within their body and helps them in locomotion, respiration and food and waste transportation. This typical circulatory system is known as water-vascular system.

Question 20.
What is notochord?
Answer:
Notochord is a rod-shaped, cartilaginous, axial supporting structure, typically possessed by all embryonic and some adult chordates. It forms the primitive axis of embryo among the chordates. It is made up of cells derived from mesoderm.

Question 21.
What is nerve cord?
Answer:
Nerve cord is a tubular structure, situated longitudinally along the dorsal side of the notochord in chordates. This is ectodermal in origin and is composed of nerve cells. In vertebrates, the anterior bulbous portion of nerve cord forms the brain and the posterior tubular portion becomes the spinal cord.

Question 22.
What are pharyngeal gill slits?
Answer:
Pharyngeal gill slits are paired pores, situated laterally at two opposite sides of the pharynx of all embryonic and several adult chordates. These pores are equipped with well-vascularised structures (gills), which act as respiratory organs that help to breath in amniotic fluid.

Question 23.
What are Protozoa?
Answer:
All the unicellular, eukaryotic, microscopic organisms, which belong to the kingdom Protista, are called Protozoa. Example-Amoeba, Paramoecium etc.

Question 24.
What are Parazoa?
Answer:
The primitive type of multicellular organisms under kingdom Animalia, having no specific tissues, organs or organ systems, are called Parazoa. Example-Sponges.

Question 25.
What are Metazoa?
Answer:
All the multicellular organisms under kingdom Animalia, having well-differentiated tissues, organs and organ systems, in order to carry out various physiological activities, are called Metazoa. Example-Sea anemones, earthworms, fishes etc.

Question 26.
What is Porifera?
Answer:
The phylum under kingdom Animalia, whose members possess body, composed of two layers and numerous pores and complex canal system, but lack true tissues, is called Porifera. ExampleScypha, Sycon, Spongilla etc.

Question 27.
What is Cnidaria?
Answer:
The phylum under kingdom Animalia, whose members are the diploblastic animals having a central body cavity with a single opening and tentacles equipped with stinging cnidoblast cells, is called Cnidaria. Example-Aurelia aurita (jellyfish), Metridium sp. (sea anemone) etc.

Question 28.
What is Ctenophora?
Answer:
The phylum under kingdom Animalia, whose members are marine, diploblastic, acoelomate, bisexual, having biradially symmetrical body and eight equidistant comb-like meridional cilliary plates along the body surface, is called Ctenophora. Example-Hormiphora, Beroe etc.

Question 29.
What is Platyhelminthes?
Answer:
The phylum under kingdom Animalia, whose members are triploblastic, bilaterally symmetrical animals with acoelomate, dorsiventrally flat body is called Platyhelminthes. Example-Planaria (flatworm), Taenia (tapeworm), Fasciola (liver fluke) etc.

Question 30.
What is Nematoda or Nemathelminthes or Ascheiminthes?
Answer:
The phylum under kingdom Animalia, whose members are triploblastic, with unsegmented, tubular, pseudocoelomic and bilaterally symmetrical body is called Nematoda or Nemathelminthes or Aschelminthes. ExampleAscaris (round worm), Wuchereria (filarial worm) etc.

Question 31.
What is Annelida?
Answer:
The phylum under kingdom Animalia, whose members are triploblastic, having true coelome and body transversely segmented into a number of ring-shaped somites or metameres, is called Annelida. Example-Pheretima (earthworm), Hirudinaria (leech) etc.

Question 32.
What is Arthropoda?
Answer:
The phylum under kingdom Animalia, whose members are triploblastic, having bilaterally symmetrical body, covered with chitinous exoskeleton and paired jointed appendages, is called Arthropoda. Example-Palaemon (prawn), Periplaneta (cockroach) etc.

Question 33.
What is Mollusca?
Answer:
The phylum under kingdom Animalia, whose members are triploblastic, coelomate, asymmetric or bilaterally symmetrical, having soft, unsegmented body, with visceral organs covered by a typical muscular membrane named mantle and the entire body covered with hard calcareous shell, is called Mollusca. Example-Pila (apple snail), Achatina (garden snail) etc.

Question 34.
What is Echinodermata?
Answer:
The phylum under kingdom Animalia, whose members are triploblastic, coelomate, pentaradially symmetrical, with numerous spines or ossicles on skin and unique water-vascular system in the body, is called Echinodermata. Example-Asterias (starfish), Cucumaria (sea cucumber) etc.

Question 35.
What is Chordata? Give example.
Answer:
The phylum under kingdom Animalia, whose members are diploblastic, coelomate, bilaterally symmetrical, which, at any phase of their life cycle possess notochord, dorsal tubular nerve cord, pharyngeal gill-slits and a post anal tail, is called Chordata. Example-Shark, toad, lizards, birds, mammals, etc.

Question 36.
How many sub-phyla are there under phylum Chordata? Name them.
Answer:
There are three sub-phyla under phylum Chordata. They are-Urochordata, Cephalochordata and Vertebrata.

Question 37.
What is Protochordata?
Answer:
The animals under phylum Chordata, in which notochord is not replaced by vertebral column, are called protochordates. The group which consists of these animals, is called Protochordata. Members of the sub-phyla Urochordata and Cephalochordata belong to this group.

Question 38.
What is Hemichordata? Give example.
Answer:
The phylum under kingdom Animalia, whose members are triploblastic, coelomate, with worm-like body divisible into proboscis, collar and trunk, having a dorsal tubular nerve cord and a number of paired pharyngeal gill slits, is called Hemichordata. ExampleBalanoglossus, Saccoglossus etc.

Question 39.
What is Urochordata or Tunicata?
Answer:
The sub-phylum under phylum chordata, the body of whose members is covered with a thin and transparent coat or tunic and their larvae possess the notochord restricted at the tail region, is called Urochordata or Tunicata. ExampleAscidia, Doliolum, Salpa etc.

Question 40
What is Cephalochordata or Acrania?
Answer:
The sub-phylum under phylum Chordata whose members are free-swimming, marine, having small lanceolate body and a well developed notochord extending from head to tail, is called Cephalochordata or Acrania. ExampleBranchiostoma, Asymmetron etc.

Question 41.
What is Vertebrata?
Answer:
The members of phylum Chordata, which possess a cranium, vertebral column and a welldeveloped endoskeleton, are called vertebrates and the sub-phylum is called Vertebrata. Example-Fishes, toads, dogs etc.

Question 42.
What is Agnatha?
Answer:
The vertebrates, which have a mouth without jaws, belong to a superclass called Agnatha. Example-Petromyzon (lamprey) etc.

Question 43.
What is Cyclostomata?
Answer:
The vertebrates, which have a round, jawless suctorial mouth, cartilaginous endoskeleton and a single nostril, belong to the class Cyclostomata. Example-Myxine (hagfish).

Question 44.
What is Gnathostomata?
Answer:
The vertebrates, whose mouth is guarded by a pair of jaws, having bony endoskeleton and two external nostrils, belong to a super-class called Gnathostomata. Example-Sharks, toads, mammals etc.

Question 45.
What is Chondrichthyes or Elasmobranchii?
Answer:
The class under kingdom Animalia, which includes jawed vertebrates, having cartilaginous endoskeleton, placoid scales on skin, mouth at the ventral side of the head and heterocercal or unevenly lobbed tail fin, is called Chondrichthyes or Elasmobranchii. Example-Scoliodon (shark), Dasyatis (stingray).

Question 46
What is Osteichthyes or Teleostomi?
Answer:
Osteichthyes or Teleostomi is a class under kingdom Animalia, which includes jawed vertebrates, having bony endoskeleton, paired gills covered with operculum, anteriorly placed mouth and homocercal or evenly lobbed tail fin. Example-Labeo rohita (rohu fish), Catla catla (catla fish) etc.

Question 47.
What is Amphibia?
Answer:
Amphibia is a class under kingdom Animalia, which includes cold-blooded vertebrates, with bony endoskeleton, which perform reproduction, spend larval life in aquatic environment but on maturity spend most of their life on land, have their body covered with naked, moist glandular skin and have a three-chambered heart. Example-Duttaphrynus (toad), Rana (frog) etc.

Question 48.
What is Reptilia?
Answer:
Reptilia is a class under kingdom Animalia, which includes cold-blooded vertebrates, whose body is covered with dry epidermal scales or scutes, have pentadactyl limbs with clawed digits (exception snakes) and perform respiration with the help of lungs. Example-Calotes (garden lizard), Naja (cobra) etc.

Question 49.
What is Aves?
Answer:
Aves is a class under kingdom Animalia, which includes warm-blooded vertebrates, whose body is covered with feathers, jaws modified into beaks, fore limbs modified into wings and have four-chambered heart. Example-Corvus (crow), Pavo (peacock) etc.

Question 50.
What is Mammalia?
Answer:
Mammalia is a class under kingdom Animalia, which includes warm-blooded vertebrates having body hair, a pair of pinnae at two sides of the head and the female members possess mammary glands to feed milk to their offsprings. Example-Canis (dog), Felis (cat) etc.

Question 51.
Which animals are called poikilothermic or cold-blooded animals?
Answer:
Body temperature of certain animals increases and decreases according to the rise and drop of environmental temperature. These animals are called poikilothermic or cold-blooded animals. Example-Fishes, amphibians and reptiles.

Question 52.
Which animals are called endothermic or homoeothermic or warm-blooded animals? Give examples.
Answer:
Body temperature of certain animals does not fluctuate with the change in environmental temperature. These animals are called endothermic or homoeothermic or warm blooded animals. Example-Birds and mammals.

Long Questions and Answers : (5 marks for each question)

Question 1.
Schematically represent the classification of animal kingdom with one example each.
Answer:
Schematic representation of the classification of animal kingdom.

Question 2.
Mention the identifying features of phylum Porifera. Give two examples with scientific names.
Answer:
Identifying features of phylum Porifera
The identifying features of phylum Porifera are as follows-

• Body is multicellular, without well-developed tissue system.
• Body is arranged in two layers and jelly-like mesenchyme is present in between these two layers.
• Exoskeleton is hard and rigid, made up of calcium or silicon-rich cells, called spongin fibres or spicules.
• One large aperture, called osculum is present at the upper end of the body. There are numerous tiny pores, called ostia, spreaded all over their body.
• Water flows continuously in the body through pores, interconnected canals and chambers.

Example with scientific names:
Two examples of the members of phylum Porifera are Neptune’s cup (Poterion neptuni) and freshwater sponge (Spongilla lacustris).

Question 3.
Mention the identifying features of phylum Cnidaria. Give two examples with scientific names.
Answer:
Identifying features of phylum Cnidaria

The identifying features of phylum Cnidaria are as follows-

• Members of this group live in water.
• They have a soft diploblastic body, made up of ectoderm and endoderm. In between these two layers, an acellular jelly-like mesoglea is present.
• Body radially or biradially symmetrical, has a gastrovascular cavity called coelenteron. This cavity has a single opening that is surrounded by tentacles.
• Typical stinging cells, called cnidoblasts, are present on the tentacles, equipped with a special stinging structure called nematocyst, which is used to capture prey and for self-defence.

Example with scientific names:
Two examples of the members of phylum Cnidaria are hydra (Hydra viritlis) and jellyfish (Aurelia aurita).

Question 4
Mention the identifying features of phylum Ctenophora. Give two examples.
Answer:
Identifying features of phylum Ctenophora

The identifying features of phylum Ctenophora are as follows-

• Body is diploblastic, made up of ectoderm and endoderm and bi-radially symmetrical. In between ectoderm and endoderm, a layer of jelly-like substance called mesenchyme is present.
• Body distinguishable into oral and aboral ends. The aboral end consists of a sensory structure, called statocyst.
• Eight quidistant longitudinal ciliary plates or comb plates are present on the body that help in locomotion.
• Typical adhesive cells, called colloblast cells or lasso cells are present in the tentacles. These colloblast cells help in capturing prey during predation.

Example of Ctenophores
Two examples of the members of phylum Ctenophora are Hormiphora plumosa and Beroe forskalii.

Question 5.
Mention the identifying features of phylum Platyhelininthes. Give two examples with scientific names.
Answer:
Identifying features of phylum Platyheiminthes

The identifying features of phylum Platyhelminthes are as follows-

• Body is dorsiventrally flat, so are called flatworms and externally covered by syncytial membrane. Their body is bilaterally symmetrical.
• Body wall is composed of three germinal layers-ectoderm, mesoderm and endoderm. Hence, they are triploblastic.
• Body cavity or coelom is absent. Body consists of a distinct head region and a prominent sucker at the mouth.
• Except reproductive system, other organ systems are not well developed. Excretion occurs by flame cells or protonephridia.
• All members of this group are hermaphrodite, i.e., bisexual.
• They may be free-living or parasitic.

Example with scientific names
Two examples of the members of phylum Platyhelminthes are tapeworm (Taenia solium) and liver fluke (Fasciola hepatica).

Question 6.
Mention the identifying features of phylum Nemathelminthes or Nematoda. Give two examples with scientific names.
Answer:
Identifying features of phylum Nemathelminthes or Nematoda

The identifying features of the phylum Nemathelminthes are as follows-

• Body is bilaterally symmetrical, long and cylindrical.
• They are triploblastic, i.e., body wall composed of three germinal layers-ectoderm, mesoderm and endoderm.
• Body is unsegmented and is covered with thick cuticle.
• A very narrow, fluid-filled body cavity or pseudocoelom is present. Organ systems are poorly developed.
• Members of this group are unisexual, i.e., with separate male and female individuals.

Example with scientific names:
Two examples of the members of phylum Nematoda are filarial worm (Wuchereria bancrofti) and hookworm (Ancylostoma duodenale).

Question 7.
Mention the identifying features of phylum Annelida. Give two examples with scientific names.
Answer:
Identifying features of phylum Annelida

The identifying features of phylum Annelida are as follows

• Body is composed of several ring-like segments called metameres or annuli. Hence, they are named annelids.
• Body is bilaterally symmetrical and triploblastic, i.e.body wall divided into ectoderm, mesoderm and endoderm.
• True body cavity or coelom is present. Organs are well differentiated.
• The annelids use setae and parapodia for locomotion.
• Each body segment bears a pair of nephridia, which act as excretory organs.

Example with scientific names
Two examples of the members of phylum Annelida are earthworm (Pheretima posthuma) and sand worm (Nereis virens).

Question 8.
Mention the identifying features of phylum Arthropoda. Give two examples with scientific names.
Answer:
Identifying features of phylum Arthropoda

The identifying features of phylum Arthropoda are as follows –

• Body is bilaterally symmetrical and externally segmented.
• The organisms have paired jointed appendages for locomotion.
• Body wall composed of ectoderm, mesoderm and endoderm, i.e., they are triploblastic.
• Body generally differentiated into head, thorax and abdomen. In some cases, head and thorax fuse together, forming cephalothorax.
• Thick and rigid exoskeleton is present, which is made up of chitin.
• Circulatory system is open, i.e., blood flows in coelomic body cavity, which is called haemocoel.

Example with scientific names
Two examples of the members of phylum Arthropoda are cockroach (Periplaneta americana), housefly (Musca domestica).

Question 9.
Mention the identifying features of phylum Mollusca. Give two examples with scientific names.
Answer:
Identifying features of phylum Mollusca

The identifying features of phylum Mollusca are as follows-

• Body is soft, bilaterally symmetrical, unsegmented and muscular.
• Body of most of the members are enclosed within a hard caicareous shell, made up of calcium carbonate.
• Visceral mass remains covered with a muscular membrane, called mantle.
• They have reduced body cavity and open circulatory system.
• Body bears kidney-like organs for excretion. They perform respiration by a single or a pair of gill-like organs present within pulmonary sac or by means of ctenidia.
• A special apparatus, called radula, is present at the base of mouth. It bears rows of chitinous teeth, which help in scrapping or cutting food.
• Creeping members of this phylum have muscular foot and swimming members have undulating membrane for lacomotion.

Example with scientific names
Two examples of the members of phylum Mollusca are garden snail (Achatina fulica) and squid (Loligo vulgaris).

Question 10.
Mention the identifying features of phylum Echinodermata. Give two examples with scientific names.
Answer:
Identifying features of phylum Echinodermata

The identifying features of phylum Echinodermata are as follows-

• Body is triploblastic, i.e., body wall made up of ectoderm, mesoderm and endoderm and body is pentaradially symmetrical.
• Body differentiated into oral and aboral surfaces.
• Body surface bears numerous spines and their endoskeleton consists of hard, calcareous ossicles, that are made up of calcium carbonate.
• Oral surface of the body has five radial ambulacra with distinct ambulacral grooves.
• They have a proper coelomic cavity and wellorganised water-vascular system that is used for circulation.
• Numerous tube feet are present on either side of the ambulacral grooves, which help in locomotion.

Example with scientific names
Two examples of the members of phylum Echinodermata are starfish (Asterias rubens), and sea cucumber (Cucumaria frondosa).

Question 11.
Mention the Identifying features of phylum Hemichordata. Give two examples.
Answer:
Identifying features of phylum Hemichordata

The identifying features of phylum Hemichordata are as follows-

• Members of this group are Balanoglossus soft bodied, coelomate, worm-like, marine animals.
• Body is divided into proboscis, collar and trunk.
• Paired pharyngeal gill slits are present in the trunk.
• They are devoid of endoskeleton and notochord.
• The nerve cord is dorsally placed, which is rod-like in most members, but hollow in few.
• A small diverticulum is present near oesophagus, called stomochord, which is a flexible hollow tube that helps to communicate with oral cavity.
• They possess an independent larval stage, named tornaria larva, at initial stage of their life cycle.

Examples of hemichordates
Two examples of hemichordates are Balanoglossus gigas and Saccoglossus sp.

Question 12.
Mention the Identifying features of phylum Chordata. Give two examples.
Answer:
Identifying features of phylum Chordata
The identifying features of phylum Chordata are as follows-

• A tubular nerve cord is present at dorsal side of the body.
• Below the dorsal tubular nerve cord, the animals possess a rod-shaped supporting structure, called notochord. It remains throughout their life or at least during embryonic stage.
• Paired pharyngeal gill slits are present throughout or, at certain period of their life cycle.
• All members have a post anal tail or at least some remains of it.
• The members under this phylum possess closed circulatory system.

Example of chordates
Two examples of chordates are Branchiostoma lanceolatum and Homo sapiens sapiens.

Question 13.
Distinguish between chordates and non-chordates.
Answer:
Differences between chordates and non-chordates

Features	Chordates	Non-chordates
1. Notochord	Present throughout or at certain stage of life cycle	Completely absent
2. Nerve cord	Tubular structure, present at the dorsal side of the body	Thread-like structure, present at the ventral side of the body
3. Vertebral column	Present in most members	Completely absent
4. Skull	Present and made up of bones and cartilages	Absent
5. Circulatory system	Closed circulatory system with arteries, veins and capillaries	Open circulatory system with arteries and veins, but capillaries are absent

Question 14.
Mention the identifying features of sub-phylum Urochordata. Give two examples.
Answer:
Identifying features of sub-phylum Urochordata

The identifying features of sub-phylum Urochordata are as follows

• Sac-like soft body of the members is covered by a membrane called tunic.
• Paired pharyngeal gill slits are present in adults. The pharyngeal region is surrounded by a membrane-bound cavity, called atrium.
• Notochord and nerve chord present during larval stage.
• Free-swimming tadpole stage is observed during the life cycle of the organisms. They undergo retrogressive metamorphosis by losing notochord and nerve cord on maturity.

Example of urochordates
Two examples of urochordates are Ascidia mentula and Doliolum denticulatum.

Question 15.
Mention the identifying features of sub-phylum Cephalochordata. Give two examples.
Answer:
Identifying features of sub-phylum Cephalochordata

The identifying features of sub-phylum Cephalochordata are as follows-

• This sub-phylum includes small fish-like animals with indistinct head. Body is bilaterally symmetrical, triploblastic and with coelomic body cavity.
• Notochord is well developed, which contracts and expands and extends from head to tail.
• Dorsal tubular nerve cord and paired pharyngeal gill slits are present.
• A typical ciliated groove, called endostyle, is present at the ventral wall of pharynx.
• Oral opening is laterally guarded by two flap-like structures, called oral hoods, with ciliated edge.

Example of cephalochordates
Two examples of cephalochordates are Branchiostoma lanceolatum and Asymmetron inferum.

Question 16
Mention the identifying features of sub-phylum Vertebrata or Craniata. Give two examples with scientific names.
Answer:
Identifying features of sub-phylum Vertebrata or Craniata
The identifying features of sub-phylum Vertebrata are as follows-

• Members of this group are bilaterally symmetrical, triploblastic and with coelomic body cavity.
• Notochord is replaced by a true vertebral column. Body possesses internal skeleton, made up of bones and cartilage.
• Brain remains protected inside cranium.
• Dorsal tubular nerve cord emerges from base of the brain and passes through the vertebral column.
• Two pairs of joint limbs present, which help in locomotion.

Example with scientific names
Two examples of the members of sub-phylum Vertebrata are rohu fish (Labeo rohita) and cat (Felis domesticus).

Question 17.
Mention the identifying features of super-class Agnatha with two examples. Mention the identifying features of super-class Gnathostomata with two examples.
Answer:
Identifying features of super-class Agnatha

The identifying features of super-class Agnatha are as follows-

• Body is elongated, with cartilaginous endoskeleton.
• Suctorial mouth is present without any jaw.
• Only a single external nostril is present.
• A number of pharyngeal gill slits are present along the two opposite sides of the body.

Example – Two examples of the members of super-class Agnatha are lamprey (Petromyzon marinus) and hagfish (Myxine glutinosa).

Identifying features of super-class Gnathostomata
The identifying features of super-class Gnathostomata are as follows-

• The mouth of the animals under this super-class is guarded by a pair of jaws.
• They have two external nostrils.
• Endoskeleton is made up of either bone or cartilage

Example- Two examples of the members of super-class Gnathostomata are shark (Scoliodon sorrakowah) and crocodile (Crocodylus porosus).

Question 18.
Mention the identifying features of class Cyclostomata. Give two examples with scientific names.
Answer:
Identifying features of class Cyclostomata

Cyclostomata is the only class under super-class Agnatha. Its characteristic features are as follows:

• The animals under this class are cold-blooded. Mouth has no jaw. Oral opening has a circular sucker, which is guarded by papillae or small tentacles.
• One medial external nostril is present.
• Body is long, cylindrical, tapering towards the tail.
• The members do not have distinct stomach or any appendages.
• Fertilisation, as well as development, both are external.
• They possess unpaired fins and do not have body scales.
• Skull and endoskeleton, both are cartilaginous.
• Heart is two-chambered, 6-14 pairs of gills present in sac.

Example with scientific names
Two examples of the members of class Cyclostomata are lamprey (Petromyzon marinus) and hagfish (Myxine glutinosa).

Question 19
Mention the identifying features of class Chondrichthyes. Give two examples with scientific names.
Answer:
Identifying features of class Chondrichthyes

The identifying features of class Chondrichthyes are as follows-

• The animals under this class Shark are cold-blooded and bilaterally symmetrical.
• Members of this group have streamlined body and cartilaginous endoskeleton.
• Body is covered with minute placoid scales.
• About 5-7 pairs of gill slits present at the lateral side of the body and are without operculum.
• Mouth present at the ventral side of the head.
• Body has paired and unpaired fins, with fin rays. Air bladder typically absent.
• They possess heterocercal tail, i.e., with two unequal lobes. Anal fins of male form claspers, which help to deposit sperms.

Example with scientific names
Two examples of the members of class Chondrichthyes are shark (Scoliodon sorrakowah) and sawfish (Anoxypristis cuspidata).

Question 20.
Mention the identifying features of class Osteichthyes. Give two examples with scientific names.
Answer:
Identifying features of class Osteichthyes

The identifying features of the class Osteichthyes are as follows

• The animals under this class are bilaterally symmetrical and are cold-blooded animals.
• They have streamlined body covered with ganoid, cycloid or ctenoid scales.
• Their endoskeleton and fin rays are made up of bones.
• Four pairs of gills present in gill chambers on either side of head. Each gill Rohu fish chamber remains covered with a bony plate, called operculum.
• Five pairs of gill arches and one pair of external gill slits present.
• They have paired or unpaired fins, with bony fin rays.
• Tail fin is homocercal with identical lobes.
• A typical swim bladder is present in the body.

Example with scientific names
Two examples of the members of class Osteichthyes are rohu fish (Labeo rohita) and catla fish (Catla catla).

Question 21.
Mention the identifying features of class Amphibia. Give two examples with scientific names.
Answer:
Identifying features of class Amphibia

The identifying features of class Amphibia are as follows-

• The animals belonging to this class are cold-blooded animals.
• Body is differentiated into head and trunk, without distinct neck.
• Body is covered with naked, moist, glandular skin without scales.
• Larvae live in water and respire with external gills. Adults are terrestrial and respire with lungs, but apart from this, skin and buccopharyngeal cavity also participate in respiration.
• Forelimbs have four and hind limbs have five digits each. The digits are without claws.
• They have three-chambered heart, with two auricles and one ventricle.

Example with scientific names
Two examples of the members of class Amphibia are toad (Duttaphrynus melanostictus) and frog (Rana tigrina).

Question 22.
Mention the identifying features of class Reptilia. Give two examples with scientific names.
Answer:
Identifying features of class Reptilia

The identifying features of class Reptilia are as follows –

• The animals under this class are cold-blooded animals.
• Body is covered with large dermal plates or dry epidermal scales, called scutes.
• They perform locomotion by crawling.
• Each of the fore and hind limbs have five clawed digits. (exception-snakes are limbless).
• Body is distinctly divisible into head, neck, trunk and tail. Cloaca is present transversely near the base of the tail.
• They generally have three chambered heart, with two auricles and a partially divided ventricle (exception – crocodile has four-chambered heart with completely divided ventricle).

Example with scientific names
Two examples of the members of class Reptilia are garden lizard (Calotes versicolor) and crocodile (Crocodylus porosus).

Question 23
Mention the identifying features of class Aves. Give two examples with scientific names.
Answer:
Identifying features of class Aves

The identifying features of the class Aves are as follows-

• The animals belonging this class are warm-blooded animals.
• Body is spindle-shaped and covered with feathers.
• Forelimbs are modified into wings.
• Their bones are hollow due to the presence of air cavities. This helps to reduce their weight and help in flying.
• Besides lungs, they have 9 air sacs, which help in flight.
• Urinary bladder, rectum and right ovary absent in order to reduce body weight.
• Teeth completely absent and jaws are modified into beaks.
• They have four-chambered heart with two auricles and two ventricles.

Example with scientific names
Two examples of the members of class Aves are crow (Corvus splendens) and pigeon (Columba livia).

Question 24
Mention the identifying features of class Mammatia. Give two examples with scientific names.
Answer:
Identifying features of class Mammalia

The identifying features of class Mammalia are as follows-

• The animals under this class are warm-blooded animals and their bodies are bilaterally symmetrical.
• Body is covered with hair. Sweat and sebaceous glands are present in the skin.
• The female members of this group have milk-producing mammary glands, for nourishing their young ones.
• A pair of external ears or pinnae is present on either side of the head.
• Respiration occurs by a pair of lungs.
• They have two pairs of limbs, used for locomotion, digging, holding or feeding.
• They are viviparous animals, i.e., give birth to young ones.
• Heart is four-chambered with two auricles and two ventricles and has left aortic arch.

Example with scientific names
Two examples of the members of class Mammalia are man (Homo sapiens sapiens) and deer (Axis axis).